Process for preparing transparent/semi-transparent color dispersions and the color dispersions made thereof

ABSTRACT

This invention relates to a process for preparing color dispersions comprising a first step of contacting water, a first colorant, and a polysaccharide selected from methylcellulose, hydropropylmethylcellulose, hydroxyethylmethylcellulose, hydroxybutylmethylcellulose, hydroxyethylethylcellulose, and the mixture thereof, to form a first colorant dispersion; a second step of contacting the first colorant dispersion with a protective composition comprising an aqueous dispersion of polymer particles, clay, and a peptizing agent to form a dispersion of protected first colorant particles; an optional third step of repeating the first step and the second step with a second colorant that is different from the first colorant to form a dispersion of protected second colorant particles; and an optional fourth step of mixing the dispersions of protected first and second colorant particles to form a multi-color dispersion. This invention also relates to a color dispersion comprising the first colorant dispersion, and a color coating comprising the color dispersion.

FIELD OF THE INVENTION

This invention relates to a process for preparingtransparent/semi-transparent color dispersions, the color dispersionsmade thereof, and a coating composition comprising the same. Inparticular, the color dispersions are multi-color.

INTRODUCTION

Multi-color coatings are water-based spray-on seamless alternatives totraditional single color coatings. Traditional single color coatingscontain one colorant. Multi-color coatings contain at least twocolorants with different colors. After spraying, colorant particles aredistributed on surfaces to simulate natural stone surfaces or othernatural multi-color surfaces. The resultant ornamental and durablemulti-color surfaces make the final coatings desirable for architecturalrenovation or new construction.

The core part of multi-color coatings is a binder system protecting andseparating the colorant particles. The binder system plays a criticalrole in determining the cost and the performance of the final coatings.Without the proper binder systems, multi-color coatings would requirestringent storage and processing conditions, or would look obviouslyunnatural. Without the proper binder systems, the colorants might alsoeasily release from the binder in water conditions to destroymulti-color performance.

Transparent or semi-transparent coating appearance is a researching hotspot of recent years. This performance is hard to be achieved by regularbinder system.

It is still desirable to find a simple process for preparing colorcoatings, particularly multi-color coatings, which are stable, withcolorant properly protected, and have specially required transparent orsemi-transparent appearances.

SUMMARY OF THE INVENTION

The present invention provides a process for making a color dispersioncomprising a first step of contacting water, a first colorant, and apolysaccharide selected from methylcellulose,hydropropylmethylcellulose, hydroxyethylmethylcellulose,hydroxybutylmethylcellulose, hydroxyethylethylcellulose, and the mixturethereof, to form a first colorant dispersion; the first colorantdispersion comprises based on the total weight of the dispersion, from0.05 wt. % to 10 wt. % of the first colorant, from 0.05 wt. % to 10 wt.% of the polysaccharide.

The second step of the process is to contact the first colorantdispersion with a protective composition comprising an aqueousdispersion of polymer particles, clay, and a peptizing agent to form adispersion of protected first colorant particles; the protectivecomposition comprises based on the total weight of the protectivecomposition, from 10 wt. % to 70 wt. % of the polymer particles, from0.05 wt. % to 10 wt. % of the clay, and from 0.05 wt. % to 2 wt. % ofthe peptizing agent; wherein the weight to weight ratio of the firstcolorant dispersion to the protective composition is from 1:30 to 5:1.

An optional third step of the process is to repeat the first step andthe second step with a second colorant that is different from the firstcolorant to form a dispersion of protected second colorant particles.

An optional fourth step of the process is to mix the dispersions ofprotected first and second colorant particles to form a two-colordispersion.

The present invention further provides a color dispersion comprising thefirst colorant dispersion.

The present invention further provides a color coating comprising thecolor dispersion.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 shows the appearances of Inventive Example 8 (FIG. 1 and a realmarble surface (FIG. 1b ).

FIG. 2 shows the appearances of Comparative Example 9 (FIG. 2a ).Comparative Example 10 (FIG. 2b ), and Comparative Example 11 (FIG. 2c).

DETAILED DESCRIPTION OF THE INVENTION

For the purpose of describing the components, all phrases comprisingparenthesis denote either or both of the included parenthetical matterand its absence. For example, the phrase “(co)polymer” includes, in thealternative, polymer, copolymer and the mixture thereof; the phrase“(meth)acrylate” means acrylate, methacrylate, and the mixture thereof.

As used herein, the term “wt. %” refers to weight percent.

The transparent/semi-transparent color dispersion of the presentinvention comprises a first colorant dispersion and a protectivecomposition. The weight ratio of the first colorant dispersion to theprotective composition is from 1:30 to 5:1, preferably from 1:25 to 4:1,and more preferably from 1:15 to 3:1.

First Colorant Dispersion

The first colorant dispersion of the present invention comprises basedon the total weight of the first colorant dispersion, from 0.05 wt. % to10 wt. %, preferably from 0.1 wt. % to 7 wt. %, and more preferably from0.5 wt. % to 5 wt. %, of a first colorant.

The colorants are organic or inorganic colorant particles, preferablyinorganic colorant particles. The illustrative examples of the colorantparticles include titanium dioxide white, carbon black, lampblack, blackiron oxide, red iron oxide, transparent red oxide, yellow iron oxide,transparent yellow oxide, brown iron oxide, phthalocyanine green,phthalocyanine blue, naphthol red, quinacridone red, quinacridonemagenta, quinacridone violet, DNA orange, and organic yellow. Thecolorants can also be particulate inorganic material which is capable ofmaterially contributing to the opacity or hiding capability of acoating.

The first colorant dispersion further comprises based on the totalweight of the first colorant dispersion, from 0.05 wt. % to 10 wt. %,preferably from 0.1 wt. % to 8 wt. %, and more preferably from 0.5 wt. %to 5 wt. %, of a polysaccharide.

Suitable examples of the polysaccharide include methylcellulose (MC),hydropropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC),hydroxybutylmethylcellulose (HBMC), hydroxyethylethylcellulose (HEEC),and the mixture thereof.

Optionally, the first colorant dispersion further comprises an aqueousdispersion of polymer particles. The polymer particles are present from0.5 wt. % to 75 wt. %, preferably from 2 wt. % to 50 wt. %, and morepreferably from 5 wt. % to 40 wt. % based on the total weight of thefirst colorant dispersion.

The first colorant dispersion may further comprise water so that thetotal weight percent of the first colorant dispersion reaches 100 wt. %.

Protective Composition

The protective composition of the present invention comprises an aqueousdispersion of polymer particles. The polymer particles are present from10 wt. % to 70 wt. %, preferably from 20 wt. % to 50 wt. %, and morepreferably from 30 wt. % to 0 wt. % based on the total weight of theprotective composition.

The protective composition further comprises from 0.05 wt. % to 10 wt.%, preferably from 0.5 wt. % to 7.5 wt. %, and more preferably from 1wt. % to 5 wt. % based on the total weight of the protectivecomposition, of a clay.

The protective composition further comprises from 0.05 wt. % to 2 wt. %,preferably from 0.1 wt. % to 1.5 wt. %, and more preferably from 0.1 wt.% to 1 wt. % based on the total weight of the protective composition, ofa peptizing agent.

The composition of the present invention may further comprise water sothat the total weight of the composition reaches 100 wt. %.

The polymer particles used in the protective composition and optionallythe first colorant dispersion of the present invention are preferablythe polymerization product of at least one ethylenically unsaturatednonionic monomer. Herein, “nonionic monomer” means that thecopolymerized monomer residue does not bear an ionic charge betweenpH=1−14. The ethylenically unsaturated nonionic monomers used in thepresent invention include (meth)acrylic ester monomers, where(meth)acrylic ester designates methacrylic ester or acrylic ester,including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexylacrylate, decyl acrylate, lauryl acrylate, methyl ethacrylate, butylmethacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethylmethacrylate, and hydroxypropyl methacrylate; (meth)acrylonitrile;(meth)acrylamide; amino-functional and ureido-functional monomers;monomers bearing acetoacetate-functional groups; styrene and substitutedstyrenes; butadiene; ethylene, propylene, α-olefins such as 1-decene;vinyl acetate, vinyl butyrate, vinyl versatate and other vinyl esters;and vinyl monomers such as vinyl chloride and vinylidene chloride.

The aqueous dispersion of polymer particles is typically formed by anaddition polymerization emulsion polymerization process as is well knownin the art. Conventional surfactants may be used, and include anionicand/or nonionic surfactants such as alkali metal or ammonium alkylsulfates, alkyl sulfonic acids, fatty acids, oxyethylated alkyl phenols,and the mixture thereof. Polymerizable surfactants that include at leastone ethylenically unsaturated carbon-carbon bond which can undergo freeradical addition polymerization may also be used. The amount ofsurfactants used is usually from 0.1 wt. % to 6 wt. % based on theweight of total monomer. Either thermal or redox initiation processesmay be used. Conventional free radical initiators may be used, such ashydrogen peroxide, t-butyl hydroperoxide, t-amyl hydroperoxide, ammoniumand alkali persulfates, typically at a level of 0.01 wt. % to 3.0 wt. %,based on the weight of total monomer. The monomer mixture may be addedin a single addition or more additions or continuously over the reactionperiod using a uniform or varying composition. Additional ingredientssuch as free radical initiators, oxidants, reducing agents, chaintransfer agents, neutralizers, surfactants, and dispersants may be addedprior to, during, or subsequent to the monomer addition.

Clays used in the protective composition are preferably hydrousphyllosilicates, with variable amounts of iron, magnesium, alkalimetals, aluminum, alkaline earths, and other cations. Suitable examplesof the clays include lithium magnesium silicate, such as LAPONITE™ RDclay and LAPONITE™ RDS clay commercially available from RockwoodAdditives Ltd., and aluminum magnesium silicate, such as VEEGUM™magnesium aluminum silicate commercially available from VanderbiltCompany, Inc.

The peptizing agents used in the protective composition are preferablysodium pyrophosphate, sodium carbonate, sodium polyphosphate, sodiummetaphosphate, sodium polyacrylate, and sodium hydroxide. Sodium ion canbe also replaced by other monovalent alkali metal ions, such as lithiumand potassium.

The color dispersion of the present invention is prepared by contactingtogether water, the first colorant, and the polysaccharide selected fromMC, HPMC, NEMC, and the mixture thereof, to make a first colorantdispersion.

In a preferred embodiment, the color dispersion of the present inventionis prepared by contacting together water, the first colorant, thepolysaccharide selected from MC, HPMC, HEMC, HBMC, HEEC, and the mixturethereof, and the aqueous dispersion of polymer particles, to make thefirst colorant dispersion.

The first colorant dispersion prepared is to contact with the protectivecomposition comprising the aqueous dispersion of polymer particles, theclay, and the peptizing agent to prepare a dispersion of protected firstcolorant particles.

The color dispersion of the present invention can have just the firstcolorant and be used to prepare a single-color coating. More than onecolor dispersions of the present invention having different colorantscan be used to prepare a multi-color coating.

A second colorant that has a different color from that of the firstcolorant can also be used in the above process, substituting the firstcolorant, to prepare a dispersion of protected second colorantparticles.

According to the requirements of different multi-color coatingapplications, a dispersion of protected third, fourth, fifth, sixth, andso on, colorant particles can be prepared by following the aboveprocess.

The dispersions of protected first and second colorant particles aremixed together to obtain a two-color dispersion. Different kinds andnumbers of dispersions of protected colorant particles could be mixedtogether to make multi-color dispersions of different needs.

Coating Composition and Application

The color dispersion is made into a coating composition by loading othercoating additives. Illustrative examples of coating additives includecoalescing agents, cosolvents, surfactants, buffers, neutralizers,thickeners, non-thickening rheology modifiers, dispersants, humectants,wetting agents, mildewcides, biocides, plasticizers, antifoaming agents,defoaming agents, anti-skinning agents, flowing agents, crosslinkers,and anti-oxidants.

Thickeners used in the present invention may include polyvinyl alcohol(PVA), hydrophobically modified alkali soluble emulsions (HASE),alkali-soluble or alkali swellable emulsions (ASE), hydrophobicallymodified ethylene oxide-urethane polymers (HEUR), cellulosic thickenerssuch as hydroxyl methylcellulose (HMC), hydroxylethylcellulose (HEC),hydrophobically-modified hydroxyethylcellulose (HMHEC), sodiumcarboxymethylcellulose (SCMC), Fumed silica, attapulgite clay and othertypes of clay, and titanate chelating agents can also be used as thethickeners of the present invention.

Dispersants used in the present invention may include non-ionic, anionicand cationic dispersants such as polyacid with suitable molecularweight, 2-amino-2-methyl-1-propanol (AMP), dimethyl amino ethanol(DMAE), potassium tripolyphosphate (KTPP), trisodium polyphosphate(TSPP), citric acid and other carboxylic acids. Preferred dispersantsare the polyacids with suitable molecular weight.

The polyacids used herein include homopolymers and copolymers based onpolycarboxylic acids, including those that have been hydrophobically orhydrophilically modified, e.g., polyacrylic acid or polymethacrylic acidor maleic anhydride with various monomers such as styrene, acrylate ormethacrylate esters, diisobutylene, and other hydrophilic or hydrophobiccomonomers as well as the salts of the aforementioned dispersants, andthe mixture thereof. The molecular weight of such polyacid dispersant isfrom 400 to 50,000, preferably from 400 to 30,000, more preferably from500 to 10,000, even more preferably from 1,000 to 5,000, and mostpreferably from 1,500 to 3,000.

Antifoaming agents and/or defoaming agents used in the present inventionmay include silicone-based and mineral oil-based defoamers. Surfactantscould be used herein include anionic, nonionic, cationic surfactants andamphiphilic surfactant. Preferably used surfactants are anionic andnonionic surfactants, and more preferably used are nonionic surfactants.

Biocides used in the present invention can be organic or inorganicbiocides. Illustrative examples are described in U.S. Pat. No. 4,127,687to DuPont, in U.S. Pat. No. 4,898,895 to Masuoka et al., and inWO1995032862A1. Preferably, the biocides have an active structure ofdiiodomethyl-p-tolylsulfone, 4,5-dichloro-2-octyl-2H-isothiazol-3-one(DCOIT), chloromethylisothiazolinone and methylisothiazolinone, and themixture thereof.

The preparation of the coating composition involves a process ofselecting and admixing appropriate coating ingredients in the correctproportions to provide coatings with specific processing and handlingproperties, as well as a final dry coating film with the desiredproperties.

The aqueous coating composition may be applied by conventionalapplication methods including brushing, roller application, and sprayingmethods such as air-atomized spray, air-assisted spray, airless spray,high volume low pressure spray, and air-assisted airless spray.

Suitable substrates include concrete, cement board, medium-density fiberboard (MDF) and particle board, gypsum board, wood, stone, metal,plastics, wall paper and textile. Preferably, all the substrates arepre-primed by waterborne or solvent-borne printers.

Examples I. Raw Materials

Ingredient Supplier guar gum (5500-6000 cps, 200 mesh) Shree RamIndustries gelatin gum (fine grade) Sinopharm Chemical Reagent Co., Ltd.METHOCEL ™ A 15 methylcellulose (A 15) The Dow Chemical CompanyMETHOCEL ™ A 4C methylcellulose (A 4C) The Dow Chemical CompanyMETHOCEL ™ A 4M methylcellulose (A 4M) The Dow Chemical CompanyMETHOCEL ™ A 40M methylcellulose (A 40M) The Dow Chemical CompanyMETHOCEL ™ F 4M The Dow Chemical Company hydroxypropylmethylcellulose (F4M) METHOCEL ™ K 100M The Dow Chemical Companyhydroxypropylmethylcellulose (K 100M) NATROSOL ™ 250 MHRhydroxylethylcellulose Ashland Aqualon Company (250 MHR) WALOCEL ™ CRT3000 carboxylmethylcellulose The Dow Chemical Company (CRT 3000)LAPONITE ™ RD clay (RD) Rockwood Additives Ltd. XERACOLOUR ™ red oxidecolorant ICC International Chemical Corporation XERACOLOUR ™ yellowoxide colorant ICC International Chemical Corporation XERACOLOUR ™ blackcolorant ICC International Chemical Corporation PRIMAL ™ AC 818 acrylicemulsion (AC 818) Dow Chemical Company PRIMAL ™ AC 261 acrylic emulsion(AC 261) Dow Chemical Company borax (chemical grade) Sinopharm ChemicalReagent Co., Ltd. sodium pyrophosphate (SPP) Sinopharm Chemical ReagentCo., Ltd.

II. Process and Method

Preparing Methods

Step a) Preparation of First Colorant Dispersion

Powders of polysaccharide were dispersed into water by stirring at200-1500 rpm for 5 min, and then incubated at 60-90° C. for 10 min withstirring at 500-2000 rpm. The system was cooled by ice water bath for 10min, and was kept stirring at 500-2000 rpm. When the polysaccharidepowders were dissolved, a first colorant, and optionally an aqueousdispersion of polymer particles were added into the solution withstirring at 2000 rpm for 20 min.

Step b) Preparation of a Dispersion of Protected First ColorantParticles

Clay and a peptizing agent were dissolved or dispersed in water withstirring at 200-2000 rpm for 30 min to make a clay dispersion. The claydispersion was mixed with an aqueous dispersion of polymer particles,with stirring at 500-2000 rpm for 30 min. The prepared first colorantdispersion in Step a) was poured into the mixture of this step, and waskept stirring at 100-1500 rpm for 5-15 min.

Step c) Preparation of a Multi-Colorant Dispersion

According to different applications, two, three, or more colorants withdifferent colors could be used in preparing the multi-color dispersions.The above steps were repeated with a second, third, or fourth colorantto make dispersions of protected second, third, or further colorantparticles if necessary. Each kind of colorant was separately protectedin the dispersion of protected colorant particles. The dispersions ofprotected first, second, third, or further colorant particles were mixedtogether, and were kept stirring at 50-2000 rpm for 30 min to make amulti-color dispersion.

Measurement

Colorant Protection

The dispersions of protected colorant particles were stirred andobserved for color release by naked eyes. If colorants were protected,no release of colorant particles was observed, even after high stirring(>600 rpm). If colorants were not protected, colorant particles werereleased in the water during or after high stirring (>600 rpm).

III. Experimental Examples

Dispersions of protected first colorant particles (dispersions 1 to 12)were prepared according to the above process. Components of eachdispersion were listed in Table 1.

TABLE 1 Components of the first colorant dispersions and the protectivecompositions First colorant dispersion Protective Composition (wt. %based on the first colorant (wt. % based on the protective composition)dispersion) Polymer Peptizing Other No. Polysaccharide PolymerDispersion Dispersion Clay agent Additives  1 A 15 1.5% AC 818 10% AC818 RD SPP — 40% 5% 0.5%  2 A 4C 1.5% AC 818 10% AC 818 RD SPP — 40% 5%0.5%  3 A 4M 1.5% AC 818 10% AC 818 RD SPP — 40% 5% 0.5%  4 A 40M 1.5%AC 818 10% AC 818 RD SPP — 40% 5% 0.5%  5 F 4M 1.5% AC 818 10% AC 818 RDSPP — 40% 5% 0.5%  6 A 40M 0.2% AC 818 10% AC 818 RD SPP — 40% 5% 0.5% 7^(#) CRT 3000 1.5% AC 818 10% AC 818 RD SPP — 40% 5% 0.5%  8 A 40M 2%AC 261 10% AC 261 60% RD SPP — 2% 0.5%  9^(#) 250 MHR 1.2% + AC 261 10%AC 261 10% RD SPP — guar 0.3% 2% 0.5% 10^(#) guar 1.1% + AC 261 10% AC261 10% RD SPP — gelatin 0.4% 2% 0.5% 11^(#) guar 1.1% + AC 261 10% AC261 10% — — Borax gelatin 0.4% 4% 12 A40M 1.0% — AC 261 10% RD SPP — 2%0.5% ^(#)Comparative examples Colorant was not shown in the table andcould be any special kind as described in the specification.

IV. Results

a) Colorant Protection

The colorant protection capability of different dispersions of protectedfirst colorant particles was shown in Table 2. To test the protectioncapability, high shearing speed (>600 rpm) was utilized when mixing thefirst colorant dispersion and the protective composition of Table 1.

The results showed that Comparative Example 7 cannot protect colorant inhigh shearing conditions, and colorant particles were released. ForInventive Example 1, 2, 3, 4, and 12, in which methylcellulose (MC) withdifferent molecular weight was utilized as the polysaccharide, colorantparticles were all successfully protected. Inventive Example 12indicated that polymer particles could be an optional component in thefirst colorant dispersion, and would not significantly influence theprotection capability.

Similarly, HPMC based polysaccharide also successfully achieved theprotection performance, as shown in Inventive Example 5. Such protectioncan also be achieved by low concentration MC/HPMC materials. As shown inInventive Example 6, MC/HPMC content was decreased from 1.5% to 0.2%,and the claimed system well protected the colorant particles.

The structure of the polysaccharide was very critical to achieve thedesired protection performance. As shown in Comparative Example 7,another type of cellulose, carboxyl methylcellulose (CMC) was used asthe polysaccharide. It showed poor colorant particle protection,

TABLE 2 The protection results by different additives^(a) No.Polysaccharide Colorant Protection^(b) 1 MC Y 2 MC Y 3 MC Y 4 MC Y 5HPMC Y 6 HPMC/MC Y 12  MC Y  7# CMC N #comparative examples; ^(a)3%(based on the total weight of the first colorant dispersion)XERACOLOUR ™ red oxide colorant was added in each dispersion ofprotected colorant particles; ratio of the first colorant dispersion tothe protective composition is 1:20; ^(b)colorant protection observed bynaked eyes; the method was listed in measurement part; Y means colorantwas protected, colorant pigments was not released after stirring; Nmeans colorant was not protected, and was released in the water duringor after stirring with high shearing force over 600 rpm.

b) Decorative Performance

Dispersions of protected colorant particles were mixed and made ofmulti-color coating compositions of the present invention. Coatingappearances were summarized in Table 3 and FIGS. 1 and 2. Multiplecolorants, selected based on different applications, were utilized tosimulate real granite appearances. The coating appearance of the presentinvention (Inventive Example 8, as shown in FIG. 1a ) was transparent orsemi-transparent with the colorants displayed in band or thread shape,similar to the real marble appearance (FIG. 1b ). For Inventive Example8, coating was sprayed on a white substrate, the white substrate can beobserved by naked eye, even in the overlap areas of different colorants.For Comparative Examples 9, 10 and 11 (as shown in FIGS. 2a, 2b, and 2crespectively), they were not transparent or semi-transparent, and thesubstrates were not observed by naked eye.

TABLE 3 The comparison of coating performance^(a) wt. % colorant, basedon the No. Polysaccharide total weight of the first colorant dispersion8 MC/HPMC 1% Red, 1% Yellow and 1% Black  9# HEC 1% Yellow and 1% Black10# guar/gelatin 1% Red, 1% Yellow and 1% Black 11# guar/gelatin 1% Red,1% Yellow and 1% Black #comparative examples; ^(a)ratio of the firstcolorant dispersion to the protective composition is 1:8.

1. A process for making a transparent/semi-transparent color dispersioncomprising a first step of contacting water, a first colorant, and apolysaccharide selected from methylcellulose,hydroxypropylmethylcellulose, and a mixture thereof to form a firstcolorant dispersion; wherein the first colorant dispersion comprisesbased on total weight of the first colorant dispersion, from 0.05 wt. %to 10 wt. % of the first colorant, and from 0.05 wt. % to 10 wt. % ofthe polysaccharide; and a second step of contacting the first colorantdispersion with a protective composition comprising an aqueousdispersion of polymer particles, clay, and a peptizing agent to form adispersion of protected first colorant particles; wherein thecomposition comprises based on total weight of the protectivecomposition, from 10 wt. % to 70 wt. % of the polymer particles, from0.05 wt. % to 10 wt. % of the clay, and from 0.05 wt. % to 2 wt. % ofthe peptizing agent; wherein the weight to weight ratio of the firstcolorant dispersion to the protective composition is from 1:30 to 5:1;and wherein the transparent/semi-transparent aqueous color dispersioncontains substantially no organic solvent.
 2. The process for making atransparent/semi-transparent color dispersion according to claim 1further comprising contacting from 0.5 wt. % to 75 wt. % based on totalweight of the first colorant dispersion, of an aqueous dispersion ofpolymer particles in the first step.
 3. The process according to claim1, wherein the first colorant dispersion further comprises a biocideand/or a thickener.
 4. The process according to claim 1 furthercomprising a third step of repeating the first step and the second stepwith a second colorant that is different from the first colorant to forma dispersion of protected second colorant particles.
 5. The processaccording to claim 4 further comprising a fourth step of mixing thedispersions of protected first and second colorant particles to form atwo-color dispersion.
 6. The process according to claim 1, wherein thepolymer particles comprise the polymerization product of at least oneethylenically unsaturated nonionic monomer; the clay is a hydrousphyllosilicate clay; and the peptizing agent is a sodium, lithium, orpotassium pyrophosphate, carbonate, polyphosphate, metaphosphate,polyacrylate, or hydroxide peptizing agent, or a combination comprisingat least one of the foregoing.
 7. The process according to claim 6,wherein the ethylenically unsaturated nonionic monomer is a(meth)acrylic ester; a (meth)acrylonitrile; a (meth)acrylamide; anamino-functional monomer; a ureido-functional monomer; anacetoacetate-functional monomer; a styrene; a butadiene; an ethylene,propylene, or α-olefin; a vinyl ester; a vinyl monomer, or a combinationcomprising at least one of the foregoing.